The present invention relates to a break releasing device of a motor equipped in an apparatus having a mechanism locking a motor shaft when the power is turned off.
A motor driving device for driving a motor and a break releasing device for releasing an electromagnetic break, which locks a motor shaft, have been independently provided, and the electromagnetic break cannot be released by hand. Because of this independent installation of the motor driving device and the break releasing device, the following inconveniences have occurred: When a motor driving system encounters a trouble, a motor does not produce torque because a driving current stops flowing to the motor. Although no torque is available in the motor, the electromagnetic brake is released or left released. As a result, a final object of the motor shaft may drop due to its own weight when the final object works in the gravity direction. When the final object interferes with an obstacle, a servo control system detects an overload status, so that the interference status cannot be avoided because the motor cannot be driven.
The present invention addresses the problems discussed above and aims to prevent a motor brake from being released at motor""s non-driven status and provide a motor-brake-releasing-device assuring safer operation than ever.
The motor-brake-releasing-device of the present invention comprises the following elements:
an electromagnetic brake for locking a motor shaft; and
a switch disposed between the electromagnetic brake and its releasing-power-supply, and the switch being operated by an AND signal of a motor driving signal and a motor-brake releasing signal. This structure prevents the brake from being released when the motor is not driven, thus the structure assures safer operation of the motor than ever.
Another motor-brake-releasing-device of the present invention comprises the following elements:
an electromagnetic brake for locking a motor shaft;
a battery functioning as a power supply for releasing the electromagnetic brake; and
a switch disposed between the battery and the electromagnetic brake for releasing a motor brake. This structure employs the battery as the power supply for releasing the electromagnetic brake, thus it is beneficial that the motor brake can be released even when a power supply of a servo-control system is not powered on.